A gang of five masked men armed with axes and knives smashed the display windows of jewellery shops on the ground floor of the hotel on rue Cambon, near the Place Vendôme, at about 6.30pm (5:30pm GMT).
“A part of the loot was recovered scattered about during the arrest of three of the suspected robbers,” the police source said, referring to the men detained immediately after the heist.
More jewels and watches were found in a bag dropped by one of the two suspects still at large, the source added, without being able to give an estimate for the value of the goods retrieved.
Place Vendôme, home to some of Paris’s top jewellers and high-end watchmakers, has been the scene of several audacious daytime raids in recent years.
Three of the robbers, who were wearing gloves and balaclavas and carrying handguns as well as hatchets, entered the hotel from the back and smashed the display windows, according to two police sources. They tried to escape out of the back but found the doors blocked and tried to transfer the loot through a window to two accomplices waiting outside.
One of the two accomplices fled by car. The other made his getaway on a motorbike, dropping a bag of jewels in the process. The total value of the loot was estimated at €4m, a legal source close to the case told AFP.
Gérard Collomb, the French interior minister, praised the police response following the arrests. “Armed robbery at the Ritz: three of the presumed thieves already arrested by police from the 2nd arrondissement. Their sang froid, their professionalism and their quick reactions do the police proud. I am grateful to them,” Collomb tweeted.
The Ritz is owned by the Egyptian businessman Mohamed Al Fayed. It was at the Paris Ritz that Diana, Princess of Wales, dined with Fayed’s son, Dodi, on the evening they died in a car crash in August 1997.
Security was stepped up in and around Place Vendôme in 2014 after a series of thefts on luxury shops and jewellers in the square, which is also home to France’s Ministry of Justice.
In Paris in October 2016, jewellery worth €10m was stolen from the American reality TV star Kim Kardashian. Five men, some wearing jackets with police insignia, held her at gunpoint, making off with several pieces of gold and diamond jewellery.
Wednesday’s robbery comes 18 months after the Ritz reopened to guests after nearly four years of renovations and a major fire.
Agence France-Presse contributed to this report